Freeboard Calculation for ship under 24m of length

Discussion in 'Stability' started by santoo, May 11, 2011.

  1. rxcomposite
    Joined: Jan 2005
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    rxcomposite Senior Member

    I think you still have to narrow down your SOR. Is it a tug, Tug and support, firefighting, or combinations? Offshore support vessel or protected waters.

    I did a quick search under class rules available here in the BD library. ABS says vessel under 90 meters. Pat 5 Chapter 8.

    LR has rules for Special Service Craft for <24 meters as it is not classified as a ship.

    Stability seems to be the major design criteria.

    In any case, you will be looking at freeboard under 1 meter. I can send you pictures of different tugs I have surveyed for reference.
  2. Luc Vernet
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    Luc Vernet Senior N.A.

    You are of course right that MGN 280 is for workboats (and tugs are workboats) and pilot boats....and for small vessels in commercial use for "sport and pleasure" ....which I am used to call "yachts".
    I did not, however say that it is for all yachts, but should effectively not have written in such a way that is sounded that it was limited to yachts only. Thank you for correcting.

    Looking through MGN 280 for information is then "better than nothing", of course, but since the state rules take precedence and might be more stringent, this may lead to mistakes and should be consulted only for general information, not direct application, and, IMHO, not even as "design guide".
  3. santoo
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    santoo Junior Member

    I get information from my boss, this vessel get exception. So that freeboard calculation is not to be submitted to class.

    Now, I have any question about freeboard calculation.
    If my vessel has no sheer of deck, should I corr. my calculation with "corr. for sheer" (ICLL Reg. 38) ?

    I have vessel with 70m of length (tanker), and she don't have sheer...
    but I have report from class that I have to corr. the value of freeboard with corr. of sheer.

    I don't understand why class asked me to do...

    Can anyone help me... please....
  4. mg_tto
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    mg_tto New Member

    Freeboard calcs - sheer correction

    Santoo, I just came across your post but do not know if you've got answer to your question.
    The sheer correction is applied when vessel's sheer differs from the standard sheer. Basically penalty is applied (i.e. increase of freeboard) when the actual sheer is less than standard, and reduction in freeboard when the sheer exceeds the standard sheer.
    I trust this explains why class asked you to correct freeboards for sheer deficiency.

  5. premshankar
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    premshankar Junior Member

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